Individual motoneurons of arthropods can be identified anatomically and their innervation fields precisely mapped electrophysiologically. It is thus possible to determine the specificity of the connections of a single cell. The proposed research will examine the specificity of motoneuron regeneration to insect leg muscles and interactions between motoneurons supplying a single muscle. The principal goals of this project are to determine: (1) the extent to which a motoneuron regenerates specifically to its normal muscles, both in intact limbs and in preparations in which the regeneration pathway is disarranged by the presence of supernumerary limbs; (2) the factors triggering axonal sprouting of a motoneuron to supply nearby denervated muscle cells; and (3) the mechanisms by which synaptic transmission by a motoneuron is enhanced following removal of other neural inputs to the muscle innervated by the motoneuron. In addition, electrical oscillatory properties of insect muscle membranes will be examined to determine if they are significant in promoting responsiveness at particular frequencies.